I will suggest you to please check the network settings and even look for your wireless connectivity so that it will be thus easier for you to check where the problem is happening.
Some quick things before I start
A; It just started happening about 3 days ago.
B: Other computers can connect to the network.
C: I have a brand new Netgear wireless adapter with everything installed.
D: I have AT&T U-Verse and am on a 2WIRE
E. I can connect to other networks (to slow to operate though)
F. Wifi Protected setup is NOT on.
G: The network has a password (WPA2) on it.